p-block

A is a white compound of lead; on heating it gives yellow B and a colourles gas that turns limewater milky. If B is heated in air for several hours at 470oC it is converted into a scarlet powder C. C contains 90.66% lead and 9.34% oxygen by mass.

C on heating with dilute aqueous nitric acid gives a colourless solution D and a brown solid E. If sodium hydroxide solution is added to solution D, a white gelatinous precipitate is formed, which with excess sodium hydroxide solution gives a colourless solution G.

Compound E reacts with concentrated hydrochloric acid to give a white solid I and a green gas J. I is soluble in hot water but insoluble in cold, and forms soluble complex ions such as K with excess chloride ions. With potassium iodide solution J gives a brown solution of L, which on shaking with hexane gives a deep purple organic layer.

With potassium iodide solution D gives a bright yellow solid M; this is insoluble in cold water, but in hot water gives a colourless solution.

Identify all the substances A - M, and write equations for all the reactions involved.


d-block

1.
Copper reacts with 50% nitric acid to give a blue solution A and a brown gas B. If the solution A is diluted and sodium hydroxide solution added cautiously, a gelatinous blue precipitate C is obtained, which if warmed forms a black solid G.

Addition of concentrated ammonia solution to C gives a deep blue solution that contains the ion D. Addition of concentrated hydrochloric acid to C gives a green solution of the ion E, which on dilution with water gives a solution of the ion F.

If the brown gas B is passed into water a mixture of acids H and I is formed in a disproportionation reaction.

Identify A - I, giving equations for and explaining each reaction as far as possible


2.
A white powder A on heating turns yellow and evolves a gas C that turns limewater milky, as well as water vapour. The yellow residue B turns white on cooling, but will turn yellow again when heated.

B reacts with dilute sulphuric acid to give a colourless solution D. If dilute sodium hydroxide solution is added to D, a white precipitate E is produced which with excess alkali gives a colourless solution F.

With dilute ammonia solution D gives a white precipitate G; adding excess ammonia causes the mixture to become clear, giving solution H.

Identify all the substances A – H, and account as thoroughly as you can for the observations.

3.
A is a metal that reacts moderately quickly with dilute sulphuric acid to give a pale green solution B and a gas C. If solution B is allowed to crystallise, the pale green solid obtained gives on strong heating a solid H, and two gases I and J. These gases are compounds of non-metallic elements, one of which is in a different oxidation state in each compound. If J is passed into a solution of barium chloride there is a vigorous reaction and a white precipitate K is formed.

A reacts with steam in an equilibrium reaction to give a solid M, which contains A in two different oxidation states, and the gas C; this reaction was at one time used industrially to make C.

A reacts with gaseous HCl on heating to give K, a white solid, and C. Hydrated K is pale green. With chlorine, A gives a brown covalent solid L which sublimes on heating; aqueous solutions of the hydrate of L react with copper metal, and for that reason are used to etch printed-circuit boards in electronics.

Solution B gives a dirty-green precipitate D if sodium hydroxide is added; this precipitate remains in excess sodium hydroxide. The same reaction is seen with the addition of ammonia. If D is allowed to stand in air it forms a foxy-red compound E, which is also obtained if sodium hydroxide solution is added to solutions of L.

Acidified solutions of B decolourise potassium manganate(VII) solution giving the manganese-containing ion N as one of the products.

Identify all of the substances A – N, and deduce as much as you can about the processes occurring.

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Good Luck..

wah.............well........l think i will leave the questions to withoutwax...lol

wow~~ where did u get all this???

you guys want answers?

A PbCO3
B PbO
C Pb3O4
D Pb(NO3)2
E PbO2
G [Pb(OH)4]-
I PbCl2
J Cl2
K [PbCl4]2-
L I2
M PbI2

1.
A Cu(NO3)2
B NO2
C Cu(OH)2
D [Cu(NH3)4]2+
E [CuCl4]2-
F Cu2+
G CuO
H HNO3
I HNO2

2. it revolves around Pb again..i guess..
3. lazy to do..giv ans la..

Click on links below to get answers...



p block Answers

d-block Q1

d-block Q2

d-block Q3